U.S. patent application number 10/029410 was filed with the patent office on 2003-06-26 for fuel filter assembly with an integrated fuel heater.
This patent application is currently assigned to Caterpillar, Inc.. Invention is credited to Bailey, Brett M., Keyster, Eric S., Miller, Terry L..
Application Number | 20030116490 10/029410 |
Document ID | / |
Family ID | 21848860 |
Filed Date | 2003-06-26 |
United States Patent
Application |
20030116490 |
Kind Code |
A1 |
Keyster, Eric S. ; et
al. |
June 26, 2003 |
Fuel filter assembly with an integrated fuel heater
Abstract
A fuel filter assembly includes a filter assembly housing with
an annular outer surface and a fuel filter positioned within the
filter assembly housing. A heater element is positioned between the
annular outer surface of the filter assembly housing and the fuel
filter. The fuel filter assembly is part of a fuel system attached
to an engine. The filter assembly housing has an inlet and outlet.
Fuel traveling through the fuel filter is heated by the heater
element when the fuel temperature is below a predetermined
temperature. The predetermined temperature preferably corresponds
to a temperature below which paraffins form in the fuel. The
invention assists in a cold start by avoiding a clogged fuel filter
due to paraffin formation.
Inventors: |
Keyster, Eric S.; (Peoria,
IL) ; Miller, Terry L.; (Morton, IL) ; Bailey,
Brett M.; (Peoria, IL) |
Correspondence
Address: |
Michael McNeil
Liell & McNeil Attorneys PC
511 S. Madison St.
PO Box 2417
Bloomington
IN
47401
US
|
Assignee: |
Caterpillar, Inc.
Peoria
IL
|
Family ID: |
21848860 |
Appl. No.: |
10/029410 |
Filed: |
December 20, 2001 |
Current U.S.
Class: |
210/184 |
Current CPC
Class: |
F02M 37/54 20190101;
F02M 37/30 20190101; F02M 37/24 20190101; B01D 35/18 20130101; Y02T
10/12 20130101; B01D 36/003 20130101; F02B 3/06 20130101; F02M
37/32 20190101; F02M 31/125 20130101; Y02T 10/126 20130101 |
Class at
Publication: |
210/184 |
International
Class: |
B01D 035/18 |
Claims
What is claimed is:
1. A fuel filter assembly comprising: a filter assembly housing
defining an inlet and an outlet; a filter positioned in the filter
assembly housing; and a heater element positioned between the
annular outer surface and the filter.
2. The fuel filter assembly of claim 1 including an annular outer
surface with a cylindrical portion; and the heater element being
positioned adjacent the cylindrical portion.
3. The fuel filter assembly of claim 2 including a water drain
valve attached to the filter assembly housing.
4. The fuel filter assembly of claim 3 wherein the heater element
is embedded in an inner wall of the filter assembly housing.
5. The fuel filter assembly of claim 3 wherein the heater element
is a portion of a thin film heater; and the thin film heater being
at least one of attached to an inner wall of the filter assembly
housing and embedded in the inner wall of the filter assembly
housing.
6. The fuel filter assembly of claim 1 wherein the heater element
is embedded in an inner wall of the filter assembly housing.
7. The fuel filter assembly of claim 1 wherein the heater element
is a portion of a thin film heater; and the thin film heater is
attached to an inner wall of the filter assembly housing.
8. The fuel filter assembly of claim 1 wherein the heater element
is a portion of a thin film heater; and the thin film heater is
embedded in an inner wall of the filter assembly housing.
9. An engine comprising: an engine housing; and a fuel system
attached to the engine housing and including a fuel filter assembly
with a heater element positioned between a filter and an annular
outer surface of a filter assembly housing.
10. The engine of claim 9 wherein the heater element being embedded
in an inner wall of the filter assembly housing.
11. The engine of claim 9 wherein the annular outer surface
includes a cylindrical portion; and the heater element being
positioned adjacent the cylindrical portion.
12. The engine of claim 11 wherein the fuel filter assembly
includes a water drain valve attached to the filter assembly
housing.
13. The engine of claim 12 wherein the heater element is embedded
in an inner wall of the filter assembly housing.
14. The engine of claim 12 wherein the heater element is a portion
of a thin film heater; and the thin film heater being at least one
of attached to an inner wall of the filter assembly housing and
embedded in the inner wall of the filter assembly housing.
15. The engine of claim 9 wherein the heater element is a portion
of a thin film heater; and the thin film heater is attached to an
inner wall of the filter assembly housing.
16. The engine of claim 9 wherein the heater element is a portion
of a thin film heater; and the thin film heater is embedded in an
inner wall of the filter assembly housing.
17. A method of heating fuel comprising the steps of: positioning a
heater element in a fuel filter assembly between a filter and an
annular outer surface of a filter assembly housing; activating the
heater element when fuel temperature is below a predetermined
temperature.
18. The method of claim 17 wherein the step of positioning includes
a step of embedding the heater element into the filter assembly
housing.
19. The method of claim 17 wherein the step of positioning includes
a step of positioning a thin film heater adjacent the filter.
20. The method of claim 19 wherein the step of positioning includes
at least one of attaching the thin film heater to an inner wall of
the fuel filter assembly and embedding the thin film heater into
the filter assembly housing.
Description
TECHNICAL FIELD
[0001] The invention relates generally to fuel filters, and more
particularly to fuel filters utilizing a heater to eliminate
clogging of the fuel filter.
BACKGROUND
[0002] In several diesel engines today, fuel filters conduct
intense filtering of fuel before the fuel is injected in the
engines. Fuel filters separate water and remove particulates from
the fuel. However, depending on the formulation, cold weather
causes diesel fuel to thicken due to the formation of paraffins,
which in return, may clog fuel filters during a cold start.
Engineers have attempted to prevent and limit this clogging of the
fuel filters with varying methods. For instance, fuel additives
that inhibit paraffin formation have been added to diesel fuel, and
fuel blends have been altered to lower the temperature at which
paraffins will form in the fuel. Further, in colder climates, the
problem has been addressed by heating the fuel. For example, when
the vehicle or machinery has been dormant for some time, block
heaters may be connected to engine blocks in order to maintain the
engine block at a temperature above which paraffins will form.
Coils or disc shaped ceramic element heaters have been positioned
at one end of the fuel filter in order to heat the fuel as it
passes through the filter as shown in U.S. Pat. No. 5,244,571
issued to Church et al. on Sep. 14, 1993. Lastly, the heat produced
by a working engine may also warm the fuel by utilizing fuel
systems with a means to circulate warm fuel through the system as
soon as possible after a cold start.
[0003] Although fuel additives, fuel blends and heaters have
performed adequately, there is room for improvement. The fuel
blends are varied by distillers depending upon the geographic
region in which the fuel is intended for use, and thus, are not
conducive to travel from a warm to a colder climate. Also,
generally the fuel blends in which paraffins form at low
temperatures are less economic. The element heaters positioned
within the housing of the fuel filters are difficult to incorporate
into existing fuel filter designs. Positioning a coil or
disc-shaped heater below the filter element shortens the effective
length of the filter element, displaces a volume of water and fuel,
and unnecessarily utilizes energy heating the water that has been
separated from the fuel. Element heaters also have a low heating
potential due to the limited contact between the fuel and the
heater. Moreover, the recirculation of warm fuel may prevent the
formation of paraffins in cold weather after the engine has been
running, but have a limited ability to prevent the formation of
paraffins while an engine is dormant prior to and during a cold
start.
[0004] The present invention is directed to one or more of the
problems set forth above.
SUMMARY OF THE INVENTION
[0005] In one aspect of the present invention, a fuel filter
assembly has a filter assembly housing with an annular outer
surface and a filter positioned within the filter assembly housing.
The housing defines an inlet and an outlet. Between the outer
surface of the filter assembly housing and the filter is a heater
element.
[0006] In another aspect of the present invention, an engine has an
engine housing and a fuel system attached to the engine housing.
The fuel system includes a fuel filter assembly with a heater
element positioned between a filter and an annular outer surface of
a filter assembly housing.
[0007] In yet another aspect of the present invention, fuel is
heated by incorporating a heater element in a fuel filter assembly
between a filter and an annular outer surface of a filter assembly
housing. The heater element is activated when the fuel temperature
is below a predetermined temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic representation of an engine and a fuel
system according to the preferred embodiment of the present
invention;
[0009] FIG. 2 is a partially sectioned diagrammatic representation
of a fuel filter assembly according to the preferred embodiment of
the present invention.
[0010] FIG. 3a is a schematic representation of a heater element
incorporated into the filter assembly housing according to the
present invention.
[0011] FIG. 3b is a schematic representation of a heater element
incorporated into the filter assembly housing according to another
embodiment of the present invention.
DETAILED DESCRIPTION
[0012] Referring to FIG. 1, there is shown a schematic
representation of an engine 10 with an attached fuel system 9
according to the present invention. Engine 10 comprises an engine
housing 11 to which the fuel system 9 is attached. A fuel tank 12
is provided within the fuel system 9 and has an outlet 17 that is
in fluid communication with a upstream fuel supply line 14a and has
an inlet 18 that is in fluid communication with a fuel return line
20. A fuel filter assembly 40 is included within the fuel system 9
and positioned in the supply line 14. It should be appreciated that
the fuel filter assembly 40 may be attached to the engine housing
11 or the body of the vehicle or machinery. The fuel filter
assembly 40 includes a fuel transfer pump 13 mounted on a fuel
filter 16. The fuel filter 16 acts to trap precipitates and other
solids from fuel flowing through the supply line 14, and to
separate water from the fuel. The fuel transfer pump 13 has an
inlet 30 in fluid communication with upstream supply line 14a and
an outlet 31 in fluid communication with a downstream supply line
14b. The fuel transfer pump 13 is positioned to draw low pressure
fuel out of the fuel tank 12 to pressurize the fuel and circulate
the fuel to at least one fuel injector 15 provided within the
engine 10. While the present invention is described for one fuel
injector 15, it should be appreciated the present invention is
applicable to an engine 10 housing any desired number of fuel
injectors 15. The fuel injector 15 has a fuel inlet 21 that is in
fluid communication with the downstream supply line 14b and a fuel
outlet 22 in fluid communication with the return line 20. An
electronic control module 19 is in communication with the fuel
filter assembly 40 via a heater communication line 37. The
electronic control module 19 is preferably in communication with
the fuel transfer pump 13 via a pump communication line 38.
Further, a temperature sensor 41 is preferably placed in the
upstream supply line 14a in close proximity to the low pressure
inlet 30 of the fuel transfer pump 13, but could be positioned at
any other suitable location such as in fuel tank 12. The
temperature sensor 41 is in communication with the electronic
control module 19 via a temperature sensor communication line
45.
[0013] Referring to FIG. 2, there is shown a diagrammatic
representation of a fuel filter assembly 40 according to the
preferred embodiment of present invention. The fuel filter assembly
40 comprises a filter assembly housing 25, the fuel filter 16, and
a heater element 50. The fuel transfer pump 13 is preferably
included within the filter assembly housing 25. However, it should
be appreciated that the fuel transfer pump 13 can also be
positioned along the supply line 14 separate from the fuel filter
16. The heater element 50 is incorporated into the filter assembly
housing 25. The heater element 50 is at least one of embedded into
an inner wall 47 of the filter assembly housing 25, attached to the
inner wall 47 of the filter assembly housing 25, and secured
between the inner wall 47 of the filter assembly housing 25 and the
fuel filter 16. The heater element 50 is preferably a wire
comprised of material with a relatively high electrical resistance
of a type often used in constructing so called thin film heaters.
Those skilled in the art will appreciate that the heater element 50
may be of varying forms and made from varying materials with a
suitable electrical resistance. The filter assembly housing 25
includes a pump housing 29 in which the fuel transfer pump 13 is
positioned and a bowl assembly housing 27 in which the fuel filter
16 is positioned. The bowl assembly housing 27 has an annular outer
surface 46 that is preferably cylindrical. The pump housing 29
defines the inlet 30 that is in fluid communication with the
upstream supply line 14a and the outlet 31 that is in fluid
communication with the downstream supply line 14b. The pump housing
29 also defines a pressure regulation outlet 34 connected to an
inlet chamber of the fuel filter assembly 40 for venting air that
is entrained in the diesel fuel or which is trapped in the fuel
system 9 upon change of the fuel filter 16 from the fuel filter
assembly 40.
[0014] The bowl assembly housing 27 of the filter assembly housing
25 is preferably threadably secured to a filter head assembly 24,
and is removable from the filter head assembly 24. The fuel
transfer pump 13 is mounted to the filter head assembly 24 opposite
the bowl assembly housing 27 in which the fuel filter 16 is
positioned. The fuel filter 16 is disposable, and can be removed
from the bowl assembly housing 27 and replaced for maintenance
purposes. Thus, the fuel filter 16 can be replaced without
disposing of the bowl assembly housing 27 in which the heater
element 50 is incorporated. Although the present invention is
illustrated for a fuel filter 16 that is separable from the bowl
assembly housing 27, the present invention may also be utilized
with a fuel filter 16 that is attached to the bowl assembly housing
27 and is replaced along with the bowl assembly housing 27. The
fuel filter 16 illustrated is an inverted-type filter in which the
fuel filter 16 is suspended generally below the filter assembly
head 24. Those skilled in the art will appreciate that the
orientation of the fuel filter 16 and the fuel transfer pump 13 may
be inverted or positioned in various other angular orientations
defined by the dimensional constraints. The fuel filter 16 includes
a filter element 36 comprised of a medium that is suitable for
separating contaminants. The fuel element 36 defines outer
peripheral fuel passages 42 and a central fuel passage 43. The fuel
flows through the outer peripheral fuel passages 42 of the filter
element 36 so that the particulate may be removed and the water
separated from the fuel. The filtered fuel flows through the
central fuel passage 43 towards the fuel transfer pump 13 as
illustrated by the arrows in FIG. 2. The filter head assembly 24 is
sealed to the bowl assembly housing 27 so the fuel paths remain
constant. Due to its specific gravity, the water collects in the
bottom cupped-shaped area of the bowl assembly housing 27. A water
drain valve 33 is attached to the lower portion of the bowl
assembly housing 27. In order to dispose of the collected water and
to drain the bowl assembly housing 27 upon replacement of the fuel
filter 16, the water drain valve 33 may be manually opened.
Although the preferred embodiments include the water drain valve
33, other means of removing the collected water from the fuel
filter 16 can be used, including but not limited to, a removable
collection bowl attached at the lowest point of the bowl assembly
housing 27.
[0015] Referring to FIGS. 3a and 3b, there are shown schematic
representations of the heater element 50 positioned within bowl
assembly housing 27, 127 according to the preferred embodiments of
the present invention. Features of the fuel filter assembly 140
that are identical to those of fuel filter assembly 40 will be
given identical numbers. According to all preferred embodiments,
the bowl assembly housing 27, 127 includes the heater element 50
that is positioned between the annular outer surface 46 of the bowl
assembly housing 27, 127 and the fuel filter 16. The heater element
50 is positioned adjacent to the bowl assembly housing 27, 127.
Although the bowl assembly housing 27, 127 is cylindrical according
to the present invention, those skilled in the art will appreciate
that the heater element 50 can be positioned within a bowl assembly
housing 27, 127 of any shape. Incorporating the heater element 50
into the bowl assembly housing 27, 127 allows for a large
cylindrical contact surface area that is desired for rapid heating
of cold fuel.
[0016] Referring to FIG. 3a, there is shown a schematic
representation of the heater element 50 incorporated into the bowl
assembly housing 27 according to a preferred embodiment of the
present invention. According to the first preferred embodiment, the
heater element 50 is embedded into the inner wall 47 of the bowl
assembly housing 27. A resistance heater is created by passing
electric current through heater element 50 incorporated within the
bowl assembly housing 27. The heater element 50, which preferably
consists of one or more wires, is preferably positioned in a
serpentine shape and molded into the material comprising the bowl
assembly housing 27, preferably plastic. Those skill in the art
should appreciate that compression molding is the preferred method
for molding the wires of the heating element 50 into the plastic of
the bowl assembly housing 27. However, other molding methods may be
utilized. Alternatively, the heater element 50 may be first
surrounded by layers of substrate before being embedded into the
bowl assembly housing 27. The heater element 50 within the
substrates is known to those skill in the art as a thin film heater
51. The thin film heater 51 is a type of resistance heater. The
thin film heater 51 is preferably a few millimeters thick. Those
skilled in the art will appreciate that the thin film heater 51
should be thick enough to produce sufficient heat to eliminate
paraffin formation within the fuel but preferably thin enough that
it may fit within the current geometry of the fuel filter 16. The
thin film heater 51 could be molded into the inner wall 47 of the
bowl assembly housing 27, preferably though a injection molding
process.
[0017] According to the embodiment of the present invention
illustrated in FIG. 3a, a heater electrical connector 44 is
attached to the bowl assembly housing 27, preferably by molding the
heater electrical connector 44 into the bowl assembly housing 27 at
a point near the filter head assembly 24. It should be appreciated
that the heater electrical connector 44 could be molded at any
position on the bowl assembly housing 27. Further, the male and
female portions of the heater electrical connector 44 could be
molded and positioned into the housing of the filter head assembly
24 and the bowl assembly housing 27 such that an electrical
connection is established when the bowl assembly housing 27 is
attached to the filter head assembly 24. The heater electrical
connector 44 is wired to the electronic control module 19 and the
heater element 50 via the heater communication line 37. The heater
communication line 37 carries electrical current through the heater
element 50 and out the heater electrical connector 44.
[0018] Referring to FIG. 3b, there is shown a schematic
representation of the heater element 50 incorporated within the
bowl assembly housing 127 according to another embodiment of the
present invention. According to this embodiment of the present
invention, the heater element 50 is a portion of a thin film heater
151, similar to the thin film heater 51 previously discussed. The
thin film heater 151 is attached to an inner wall 147 of the bowl
assembly housing 127. The bowl assembly housing 127 is preferably
cylindrical in shape. There are varying methods for attaching the
thin film heater 151 to the bowl assembly housing 127. Preferably,
the thin film heater 151 is attached to the bowl assembly housing
127 by applying adhesives between the thin film heater 151 and the
bowl assembly housing 127. Those skilled in the art will
appreciated that the adhesives should not be soluble in diesel
fuel, should not adversely react with the chemical makeup of the
diesel fuel, and should be capable of withstanding the temperature
variations between the heater and the cold climate.
[0019] According to still another alternative embodiment of the
present invention, similar to the embodiment just discussed, the
heater element 50 is a portion of a thin film heater 251 that is
molded to the shape of the bowl assembly housing 127, which is
preferably cylindrical. However, unlike the embodiment just
discussed, the thin film heater 251 is positioned between the inner
wall 147 of the bowl assembly housing 127 and the fuel filter 16.
Preferably, the thin film heater 251 is made of a material such
that it is resiliently urged into contact with the inner wall 147
of the bowl assembly housing 127 by its own resilience from being
molded into a flexible flat shape and then rolled up to fit into
the bowl assembly housing 127. However, those skilled in the art
should appreciate that there are varying methods for securing the
thin film heater 251 between the bowl assembly housing 127 and the
fuel filter 16, including but not limited to spacers and springs.
The thin film heater 251 is attached to the neither the bowl
assembly housing 127 nor the fuel filter 16. Thus, when the bowl
assembly housing 127 is removed from the filter head assembly 24 in
order to replace the fuel filter 16, the thin film heater 251 may
be removed from both the bowl assembly housing 127 and the fuel
filter 16. This embodiment is advantageous because it allows the
bowl assembly housing 127 or the thin film heater 251 to be
replaced without replacing the other. Moreover, it eliminates the
cost of molding or attaching the thin film heater 251 to the bowl
assembly housing 127.
[0020] According to the embodiment of the present invention
illustrated in FIG. 3b, the heater element 50 is attached or
positioned within the bowl assembly housing 127 rather than
embedded into the wall of the bowl assembly housing 127. Thus, a
heater communication line 137 extends to the interior of the bowl
assembly housing 127 in order to pass electric current through the
heater element 50 contained within the thin film heater 151, 251.
In order to prevent leakage of fuel from the fuel filter 16, a
heater electrical connector 144 is preferably molded into the bowl
assembly housing 127 near the filter head assembly 24. Just as with
the other embodiments, it should be appreciated that the heater
electrical connector 144 could be molded at any position on the
bowl assembly housing 127 or incorporated into the housings of both
the bowl assembly 127 and the filter head 24. The heater electrical
connector 144 is wired to the electronic control module 19 and the
thin film heater 151, 251 via the heater communication line 137.
The heater communication line 137 carries electric current through
the heater element 50 contained within the thin film heater 151,
251 and out the heater electrical connector 144. The heater
communication line 137 preferably enters and exits the thin film
heater 151, 251 at the same end of the thin film heater 151, 251.
The portion of the heater communication line 137 that is in the
interior of the bowl assembly housing 127 is preferably insulated
with a material that is resistant diesel fuel and to the heat
produced by the thin film heater 151, 251.
[0021] In order to determine whether the fuel flowing through the
fuel filter 16 is susceptible to paraffin formation, there should
be a means for estimating the temperature of the fuel entering the
fuel filter 16. Preferably, accurate control of temperature is
achieved by a closed-loop feedback control system coded into the
electronic control module 19 in a conventional manner. Recalling
FIG. 1, a temperature sensor 41 is preferably positioned within the
upstream supply line 14a in order to measure the temperature of the
fuel flowing into fuel filter assembly 40. In order to receive the
most accurate reading of the temperature of the fuel entering the
fuel filter assembly 40, the temperature sensor 41 is preferably
positioned at a point in the fuel system 9 close to the low
pressure inlet 30 of the fuel filter assembly 40. However, the
temperature sensor 41 should be placed at a distance away from the
heater element 50 so that the temperature sensor 41 does not detect
the temperature of the heater element 50 or the fuel that is heated
by the heater element 50 as it passes through the fuel filter 16.
Those skilled in the art will appreciate that the temperature
sensor 41 can be positioned at any point along the fuel system 9,
including, but not limited to, the fuel tank 12. Further, a
temperature sensor 41 may not be required when the fuel temperature
can be estimated by using an existing temperature sensor, such as
the temperature sensor for determining the temperature of coolant
or oil. The temperature sensor 41 is in communication with the
electronic control module 19 via the temperature sensor line 45.
Once the temperature sensor 41 measures the temperature of the fuel
flowing into the fuel filter assembly 40, it communicates the
actual temperature to the electronic control module 19. The
electronic control module 19 compares the actual temperature to a
predetermined temperature. The predetermined temperature is
preferably the temperature at which paraffins do not form within
the fuel.
[0022] Referring to FIGS. 3a and 3b, if the actual temperature of
the fuel is less than the predetermined temperature at which
paraffins form, the electronic control module 19 will continue to
send electric current through the heater electrical connector 44,
144 and the heater element 50 via the heater communication line 37,
137. If the electronic control module 19 determines that the actual
temperature of the fuel is greater than the predetermined pressure,
then the electronic control module 19 will no longer permit
electric current to flow through the heater electrical connector
44, 144 and energize the heater element 50. Alternatively, an
open-loop feedback circuit may be used to control the temperature
of the fuel flowing into the fuel filter 16. In an open-loop
feedback circuit, the electronic control module 19 is configured
such that it energizes the heater element 50 for a predetermined
time period during a cold start. The predetermined time period
would be sufficiently long to dissolve the existing paraffins and
allow the heat from the engine 10 to warm the fuel so that
paraffins do not form once the heater element 50 is de-energized.
Once the predetermined time period ends, the electronic control
module 19 would no longer allow electric current flow through the
heater electrical connector 44, 144 and the heater element 50. In
still another alternative, it might be desirable to use a simple
temperature sensitive switch that ends current to the heater
element 50 above the predetermined temperature.
[0023] In still another potential enhancement according to the
present invention, the electronic control module 19 includes logic
to reduce current to the fuel transfer pump 13 during cold start.
The current level should be high enough that adequate fuel is
supplied to the fuel injectors 15 to start the engine 10 and
maintain it running, but low enough that the fuel flow rate through
the fuel filter 16 is such that the heater element 50 can more
effectively do its job. This strategy might also permit a lower
wattage heater element 50 than that required if the fuel transfer
pump 13 output were not reduced.
[0024] Industrial Applicability
[0025] Referring to FIGS. 1-3, the application of the present
invention is described for all the preferred embodiments of the
invention. At the time the ignition is activated, the temperature
sensor 41 positioned within the upstream supply line 14a detects
the temperature of the fuel within the fuel system 9. The
temperature sensor 41 communicates the actual temperature to
electronic control module 19 via the temperature sensor line 45.
The electronic control module 19 then compares the actual
temperature within the fuel system to the predetermined
temperature. Again, the predetermined temperature is preferably the
temperature below which paraffins form in the fuel. If the actual
temperature is greater than the predetermined temperature, then the
electronic control module 19 will not energize the heater element
50 via the heater communication line 37, 137. However, under cold
start conditions, the actual temperature will sometimes be less
than the predetermined temperature and be such that paraffins have
formed in the fuel. Thus, in order to dissolve the existing
paraffins and prevent further formation of paraffins, the
electronic control module 19 will energize the heater element 50 by
allowing electric current to flow through the heater element 50 via
the heater communication line 37, 137 and the heater electrical
connector 44, 144. It should be appreciated that the electronic
control module 19 can be configured such that it energizes the
heater element 50 every time the ignition is activated regardless
of the actual temperature within the fuel system 9. The electronic
control module 19 might also command the fuel transfer pump 13 to
reduce its output rate to make the heater element 50 more
effective.
[0026] The heater element 50 will begin heating the fuel filter 16
and the fuel, if any, within the fuel filter 16. Because the heater
element 50 is at least one of embedded into the bowl assembly
housing 27, attached to the bowl assembly housing 127, or secured
within the bowl assembly housing 127, the heater element 50
conforms to the preferably cylindrical shape of the bowl assembly
housing 27, 127. This maximizes the heating surface area of the
heater element 50. Whereas coils or a disc shaped heater placed at
one end of the fuel filter 16 is limited to the relatively small
heating surface area at that end of the fuel filter 16, the heating
surface area of the heater element 50 extends around the
circumference and the length of the bowl assembly housing 27, 127.
Thus, the heater element 50 will heat the fuel flowing throughout
the filter element 36 more quickly.
[0027] At the time the ignition is activated, the fuel transfer
pump 13 is energized via the pump communication line 38 and the
electrical connector 39. Fuel flows from the fuel tank 12 to the
low pressure inlet 30 of the fuel filter assembly 40, 140 via the
upstream supply line 14a. The flow path through the fuel transfer
pump 13 and the fuel filter 16 is illustrated by the arrows in FIG.
2. After the fuel enters the fuel filter assembly 40, 140, the fuel
flows via a passage (not shown) through the fuel transfer pump 13
and the filter head assembly 24. The fuel then flows through the
outer peripheral fuel passages 42 of the fuel filter element 36 of
the fuel filter 16. As the fuel transverses the filter element 36,
the fuel is in close proximity to the heater element 50 that is
positioned between the annular outer surface 46 of the bowl
assembly housing 27, 127 and the fuel filter 16. The heater element
50 is at least one of embedded in the inner wall 47 of the bowl
assembly housing 27, attached to the inner wall 147 of the bowl
assembly housing 127, or secured between the bowl assembly housing
127 and the fuel filter 16 such as by means of a disc-shaped
spring. Because the heater element 50 is already energized and the
flow path of the fuel is in close proximity to the heater element
50, the fuel will be warmed to a temperature at which paraffins
will not form and paraffins that have formed will dissolve.
Therefore, when the fuel transverses the fuel element 36 during a
cold start, there will be no paraffins to clog the fuel filter 16
and prohibit the starting of the engine 10. Rather, as the fuel
transverses the filter element 36, particulates are removed from
the fuel. Due to the specific gravity of the water, the water will
separate from the fuel and collect at the bottom of the bowl
assembly housing 27, 127. The collected water can eventually be
drained from the fuel filter 16 via the water drain valve 33. After
the fuel is filtered, it flows through the center fuel passage 43
of the fuel element 36 towards the fuel transfer pump 13. Once in
the fuel transfer pump 13, the filtered fuel is pressurized and
circulated through the fuel system 9 via the outlet 31. The fuel is
eventually delivered to at least one fuel injector15. The fuel
injector 15 injects the fuel into the engine cylinder (not shown)
in order to start the engine 10.
[0028] The fuel transfer pump 13 constantly circulates fuel within
the fuel system 9. However, not all of the fuel circulated by the
fuel transfer pump 13 is injected into the engine cylinder. The
fuel which is not injected is recirculated through the fuel system
9. The remaining unused fuel will be delivered via the return line
20 to the fuel tank 12 for reuse in the engine 10. The heat
produced by the working engine 10 will have warmed the fuel that
has been cycled through the fuel system 9 of engine 10. When the
warmed recycled fuel mixes with the cold fuel within the fuel tank
12, the cold fuel within the fuel tank 12 is warmed. The warmed
fuel is then delivered to the fuel filter assembly 40, 140 via the
upstream supply line 14a, and the cycle through the fuel system 9
will repeat itself. Each time the recycled fuel mixes with the fuel
within the fuel tank 12, the fuel within the fuel tank 12 becomes
warmer. As the fuel being delivered to the fuel filter assembly 40,
140 warms, the temperature sensor 41 preferably positioned within
the supply line 14 will periodically sample that actual temperature
of the fuel flowing into the fuel filter assembly 40, 140.
Preferably, the frequency of sampling is selected in order to
detect a mean or average temperature that is not too sensitive to
insignificant transient effects. It should be appreciated that the
temperature sensor 41 could be placed at any point along the fuel
system, 9 such as in the fuel tank 12 or a different point along
the supply line 14. The temperature sensor 41 will communicate the
temperature of the fuel to the electronic control module 19 via the
temperature sensor communication line 45. The electronic control
module 19 compares the actual temperature to a predetermined
temperature. The predetermined temperature is the temperature below
which paraffins form in the fuel causing a clogged fuel filter 16.
As long as the actual temperature of the fuel is less than the
predetermined temperature, the electronic control module 19 will
continue to allow current to be supplied across heater electrical
connector 44, 144 and through the heater element 50. Thus, the
heater element 50 will remain energized and warming the fuel.
However, when the actual temperature of the fuel flowing into the
fuel filter assembly 40, 140 is greater than the predetermined
pressure, the electronic control module 19 will stop the electric
current from flowing across the heater electrical connector 44, 144
and energizing the heater element 50. The heater element 50 will no
longer warm the fuel. At this point, the heat emitting from the
work of the engine 10 is sufficient to sustain the temperature of
the fuel so that paraffins do not form within the fuel.
[0029] The present invention improves cold starts in cold weather
by eliminating the formation of paraffins in diesel fuel that could
clog the fuel filer 16. The heater element 50 maximizes its heating
surface by conforming to the cylindrical shape of the bowl assembly
housing 27, 127 and the filter element 36. Because the heater
element 50 extends the circumference and length of the bowl
assembly housing 27, 127, it is in close proximity with most of the
fuel flowing thorough the filter element 36 and, thereby, maximizes
its heating surface area. Further, because the heater element 50
can mold to the shape of the bowl assembly housing 27, 127, it does
not consume a significant amount of space within the fuel filter 16
as does a coil or disc-shaped heater. Positioning a coil or
disc-shaped heater below the filter element 36 shortens the
effective length of the filter element 36, displaces a volume of
water and fuel, and unnecessarily utilizes energy heating the water
not yet drained through the water drain valve 33. Moreover, because
the heater element 50 is incorporated into the inner wall 47, 147
of the bowl assembly housing 27, 127, the heater element 50 can be
applied in current fuel filter assemblies by simply replacing the
bowl assembly housing 27, 127 with a bowl assembly housing 27, 127
that includes a heater element 50 and a heater electrical connector
44, 144. Unlike incorporating a disc-shaped or coil heater into a
fuel filter assembly 40, 140, incorporating a heater element 50
does not require redesigning of the entire fuel filter assembly 40,
140 and/or surrounding components. The heater element 50 does not
disrupt the flow pattern of the fuel or the design of the fuel
filter 16. In addition, because the heater element 50 is separate
from the filter element 36, the heater element 50 does not require
replacement along with replacement of the filter element 36. Those
skilled in the art should appreciate that although the present
invention has been illustrated for use in a fuel system, it could
find use in any fluid system having a need to heat the fluid and a
filter.
[0030] It should be understood that the above description is
intended for illustrative purposes only, and is not intended to
limit the scope of the present invention in any way. Thus, those
skilled in the art will appreciate that other aspects, objects, and
advantages of the invention can be obtained from a study of the
drawings, the disclosure and the appended claims.
* * * * *